A strain sensor and methods, apparatuses and computer programs for using a strain sensor

Abstract

A strain sensor comprising: a stretchable substrate comprising a plurality of layers; non-stretchable magnetic material fastened to at least one of the plurality of layers; and at least one coil of conductive thread wound through the substrate to mechanically interconnect the plurality of layers, wherein at least a portion of the at least one coil of conductive thread is located around at least a portion of the non-stretchable magnetic material.

1 .- 15 . (canceled) 
     
     
         16 . A strain sensor comprising:
 a stretchable substrate comprising a plurality of layers;   non-stretchable magnetic material fastened to at least one of the plurality of layers; and   at least one coil of conductive thread wound through the substrate to mechanically interconnect the plurality of layers, wherein at least a portion of the at least one coil of conductive thread is located around at least a portion of the non-stretchable magnetic material.   
     
     
         17 . The strain sensor as claimed in  claim 16 , comprising at least one fastener configured to fasten the non-stretchable magnetic material to at least one of the plurality of layers. 
     
     
         18 . The strain sensor as claimed in  claim 17 , wherein the fastener comprises at least one of glue or one or more stitches. 
     
     
         19 . The strain sensor as claimed in  claim 16 , wherein the non-stretchable magnetic material comprises a rounded tip. 
     
     
         20 . The strain sensor as claimed in  claim 16 , wherein the non-stretchable magnetic material comprises at least one of a magnetic strip or a magnetic fibre. 
     
     
         21 . The strain sensor as claimed in  claim 16 , wherein the stretchable substrate comprises a first non-magnetic, non-conductive layer and a second non-magnetic, non-conductive layer, and wherein the first non-magnetic, non-conductive layer and the second non-magnetic, non-conductive layer are the outer layers of the substrate. 
     
     
         22 . A method comprising:
 measuring an inductance of the strain sensor, the strain sensor comprising:
 a stretchable substrate comprising a plurality of layers; 
 non-stretchable magnetic material fastened to at least one of the plurality of layers; and 
 at least one coil of conductive thread wound through the substrate to mechanically interconnect the plurality of layers, wherein at least a portion of the at least one coil of conductive thread is located around at least a portion of the non-stretchable magnetic material; and the method comprising: 
   determining a change in the inductance of the strain sensor.   
     
     
         23 . The method as claimed in  claim 22 , comprising determining at least one physiological measurement of a subject based, at least in part, on the determined change in inductance. 
     
     
         24 . The method as claimed in  claim 23 , wherein the at least one physiological measurement comprises at least one of breathing rate, heart rate, heart rate variability, blood pressure or posturing of a body part. 
     
     
         25 . The method as claimed in  claim 22 , wherein determining a change in the inductance of the strain sensor comprises monitoring a variation of the inductance of the strain sensor over time. 
     
     
         26 . The method as claimed in  claim 22 , comprising fastening the non-stretchable magnetic material to at least one of the plurality of layers. 
     
     
         27 . The method as claimed in  claim 26 , wherein the fastening comprises gluing or stitching. 
     
     
         28 . The method as claimed in  claim 22 , comprising rounding the magnetic material. 
     
     
         29 . The method as claimed in  claim 22 , comprising sewing the non-stretchable magnetic material with at least one magnetic fibre. 
     
     
         30 . The method as claimed in  claim 22 , comprising provision of at least one output based on, at least in part, the determined change in the inductance of the strain sensor. 
     
     
         31 . A wearable electronic device comprising: a garment attached to a strain sensor comprising: a stretchable substrate comprising a plurality of layers; non-stretchable magnetic material fastened to at least one of the plurality of layers; and at least one coil of conductive thread wound through the substrate to mechanically interconnect the plurality of layers, wherein at least a portion of the at least one coil of conductive thread is located around at least a portion of the non-stretchable magnetic material. 
     
     
         32 . The wearable electronic device as claimed in  claim 31 , comprising at least one fastener configured to fasten the non-stretchable magnetic material to at least one of the plurality of layers. 
     
     
         33 . The wearable electronic device as claimed in  claim 32 , wherein the fastener comprises at least one of glue or one or more stitches. 
     
     
         34 . The wearable electronic device as claimed in  claim 31 , wherein the non-stretchable magnetic material comprises at least one of a magnetic strip or a magnetic fibre. 
     
     
         35 . The wearable electronic device as claimed in  claim 31 , wherein the stretchable substrate comprises a first non-magnetic, non-conductive layer and a second non-magnetic, non-conductive layer, and wherein the first non-magnetic, non-conductive layer and the second non-magnetic, non-conductive layer are the outer layers of the substrate.